PDF Import

Why is this happening?

I have a PDF showing proposed works that I want to import and overlay on top of the overall site plan. The PDF has two details showing proposed works in two separate locations on the site. In order to be able to overlay both details in their correct locations I have cropped the PDF to create two drawings, which i have saved as Detail1 and Detail 2.

However, when I import Detail 1 it doesn't just bring in the part I want. Somehow the software is loading the uncropped file. I've no idea how this is happening. I've even tried shutting Kubla Cubed down and restarting - didn't work. I've restarted explorer - that didn't work. Somehow Kubla Cubed seems to be able to put the cropped PDF back together again.

Please explain

Thanks

Kevin